1. Field of the Invention
The present invention relates to a correction method and a measuring instrument and, more particularly, to an improvement of a correction mechanism for correcting a measurement error due to the motion of a stylus.
2. Prior Art
Conventionally, a precision measuring instrument such as a form measuring instrument has been used to measure the form of a work. The precision measuring instrument includes a stylus and a pickup. When tracing is performed on a work in the X-axis direction by using the tip of a stylus, the stylus moves up and down following the height of work. The pickup detects the up-and-down movement of the stylus, and obtains coordinate value information of a point on the work. From the obtained coordinate value information on the work, the form is then determined.
For precision measuring instruments, highly accurate measurements are demanded as compared to general measuring instruments. However, a pivot-type stylus may cause an error in the measurement result because a stylus arm performs circular motion around a supporting point. Therefore, in precise measurements, it is very important has properly reduce measurement errors due to the circular motion.
To meet such a demand, an attempt has been made to reduce the influence of measurement errors due to the circular motion of pivot-type styluses by correcting the data measured by the pivot-type stylus using a correction algorithm described, for example, in Japanese Patent No. 2727067, Japanese Patent No. 3215325, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-500675, Japanese Unexamined Patent Application Publication No. 03-115902, and U.S. Pat. No. 5,150,314.
However, even in the above-described conventional system, regarding the correction accuracy of data measured by a stylus, further improvement has been demanded. Also, conventionally, a proper technique capable of meeting this demand has not existed.